Does the time of fasting affect complication rates during ketamine sedation

Report By: Ray McGlone - Consultant in Emergency Medicine

Search checked by Simon Carley - Consultant in Emergency Medicine

Institution: Lancaster Royal Infirmary

Original author: Ray McGlone

Original institution: Lancaster Royal Infirmary

Current web editor: Tom Bartram - middle grade A+E

Date Submitted: 4th March 2005

Last Modified: 14th August 2008

Status: Green (complete)

Three Part Question

[In children undergoing ketamine sedation] is [prolonged fasting (6 hours or more) better than short term fasting (3 hours)] at [reducing the incidence of vomiting and other complications of sedation]

Clinical Scenario

A 4 year old boy is brought to the emergency department having fallen over at home. He has sustained a 3 cm deep laceration to the forehead. He was never unconcious and you have no concerns of an underlying brain injury. The wound clearly needs closure and cleaning but he is upset and would not be able to cooperate without sedation. You suggest this but his mother states that he ate 3 hours ago. You phone the anaesthetist on call who tells you that you should wait a further 3 hours to ensure that he is fasted. You wonder if this is really necessary.

Search Outcome

Medline 1: 219 papers of which two were relevant to the three part question.Medline 2: 9 papers none of which were relevant.One additional paper was known to the author.

Relevant Paper(s)

Author, date and country

Patient group

Study type (level of evidence)

Outcomes

Key results

Study Weaknesses

Treston G2004Australia

272 consecutive children undergoing ketamine sedation in the emergency department. Results available on 257. Authors examined the relationship between fasting time and incidence of vomiting. Patients were given IV ketamine

Prospective cohort study

Incidence of vomiting in children fasted less than one hour

2/30 (6%)

Patients fasted more than 3 hours are grouped together rather than discriminated at 6 hours. Further information was sought from the original author but data differentiating patients at 6 hours was not available.

Database of 2085 children undergoing procedural sedation by emergency physicians. Age range 19 days to 32.1 years in database. Median age was 6.7 years. Fasting time documented in 1555 patients. Analysis of complication rates was divided into 0 to 2, 2 to 4, 4 to 6, 6 to 8 and greater than 8 and not documented. Sedation options were ketamine (IV or IM), midazolam/ketamine, midazolam/fentanyl, midazolam, midazolam/morphine, other.

Incomplete data collection (a quarter of charts were not completed). Specific influence of fasting time on ketamine patients unknown as all agents reported as a group. No differentiation of food vs fluids fasting.

1014 patients undergoing procedural sedation in a paediatric emergency department. A variety of different agents were used but 474 (47%) had ketamine. Fasting time against established guidelines was recorded (<6 months 4- 6 hours, 6-36 months 6 hours, >36 months 6-8 hours). Or 2 hours for clear liquids in all age groups.

Prospective case series

Data collection standards

905 (98%) had fasting status recorded.

Less than 14 patients aged less than 6 months in the study. 11% of patients did not have fasting time documented. Numerous agents used so difficult to determine if there are drug specific differences.

Comment(s)

The issue of ketamine use in the emergency department is controversial despite overwhelming evidence regarding its efficacy and safety. Recent guidelines from the Scottish Intercollegiate Guidelines Network (SIGN) have suggested that children should be starved for more than 6 hours. However, British Association of Emergency Medicine (BAEM) and American College of Emergency Physicians (ACEP) guidelines suggest that 3 hours is adequate. The papers listed above support the view that prolonged fasting is unlikely to significantly reduce vomiting or affect other complications of sedation.
Fasting is intended to reduce the incidence of pulmonary aspiration (hence the focus on vomiting rates). None of these papers had any patients with this complication and we are unaware of any reports of pulmonary aspiration following ED procedural sedation with ketamine in children. It must be noted that the incidence of vomiting is a proxy measure for aspiration of gastric contents. If vomiting occurs after the period of sedation (as is typically the case with ketamine) then it is unlikely to result in aspiration. However, what is clear, from these and other studies, is that the incidence of aspiration is low.
The first paper examines the use of IV ketamine only. The applicability of the results to IM ketamine must be inferred.